96 Passat - interior fan control module melting

[fixit13]

Looking to replace the interior fan control module with the 3 knobs on it. Does anybody know the part number for this?

I replaced my son's in his golf when it melted down with one out of a 98 jetta. Now mine is starting to go. It gets very warm and I can tell a melt down is near. His was part number 1H0 819 045 but when I search on it, it does not seem to be for the Passat. I have searched but not found it online. I know it has to be there...somewhere. Maybe it is the same?

I was just hoping to avoid pulling it out until I had the replacement in hand.

 

[Abacus]

The B4 part number is 3A0819045C and directly under that is 3A0820045A in the same tag.

 

[fixit13]

Awesome! Thank you so much!

 

[LLL]

Did you often switch on your blower on 3rd or 4th speed? Mine is not
melted, but I noticed that it goes hot when it is more then 5 min. on
the 3rd or 4th speed. The copper part on the fan knob is getting so hot,
that it melts everything around, including wires connected behind the knob.

 

[yakko]

I had a bad blower motor. It was running high current. I added in a set of three relays to eliminate the switch from getting destroyed. I did replace the blower motor.

 

[Steve Addy]

I've never seen a B4 with a melted fan control switch but I have seen B3 cars with what was clearly a hot connection at the switch. Most all b3 that I've seen are brown or charred at the connector for what I assume is the high speed setting.

I always figured that they resolved that little problem when they redesigned the AC wiring system for the B4 cars.

The radiator cooling fan system for the B3 was another somewhat bad design that I think the fan control module helped to resolve.

Steve

 

[Jetter_Sprinta]

We had this on a B4, but I think it was because I usually use low speed. It would get finger-melting hot after a very short time running on 1.


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[thechoochlyman]

My fan control knob has been getting hot on occasion. Figured it would better to investigate now rather than wait.

Is it possible to test the resistance of the blower motor to see if that's the cause of the problem?

I had a bad blower motor. It was running high current. I added in a set of three relays to eliminate the switch from getting destroyed. I did replace the blower motor.

I know this is an old post, but I'd be interested in knowing how you went about this. I was also considering running a relayed rheostat to the blower motor.

 

[vanbcguy]

If the motor is at all stiff to turn manually it'll be pulling more current than it should. Any factory lubrication that was present in the motor bushings has long ago dried up and turned to glue; it would be a reasonable PM step to add some electric motor oil to the ends of the shaft every few years.

It seems with VW the motor itself will keep on trying to work long after it has fried the resistor pack and the power switch.

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[thechoochlyman]

Is it very difficult to access?

 

[Abacus]

Not at all.

 

[thechoochlyman]

Finally getting around to acting on this, I ordered a set of four relays and pigtails on eBay. Plan on just splicing them all in under the airbag and letting it ride. At least I won't have to worry about the switch melting out even if the motor does need maintenance.

 

[thechoochlyman]

I got under the dash today and soldered a 12 gauge jumper wire directly onto the black wire that feeds power to the blower switch. I have it laying out in a good place where I can patch in the relays easily.

One question - because hi speed will work on the blower fan regardless of whether or not the resistor pack is plugged in, where should I splice in the relay for the black/red (full power) wire? If it put it in-line with the rest of the wires going to the resistor pack, I'm afraid the switch will still carry most of the load of the motor. Or can I trace the red/black wire going to the motor far enough back that I will find where it intercepts with the resistor pack?

EDIT: I just now remembered seeing a one-on-one red/black wire connection behind the HVAC panel, which I conveniently moved to where I can reach it from under the dash (so I wouldn't have to take it back apart again!). According to my Bentley diagram, this is the wire going to the blower motor which bypasses the resistor pack. What if I just unplugged it? Why are there two 12-volt wires going to the blower motor?

 

[thechoochlyman]

More findings and thoughts:
The current for speeds 1-3 goes into the resistor pack through the white/blue/green wires, and comes out the red wire into the hi-speed/blower fan + connection, yes?

Here is my relay connection plan so far:

Pin 85 on all relays - ground
Pin 87 on all relays - ignition hot, coming from back of blower motor switch
Relay 1:
Pin 86: Black/White wire from blower switch
Pin 30: Black/White wire from resistor pack
Relay 2:
Pin 86: Black/Blue wire from blower switch
Pin 30: Black/Blue wire from resistor pack
Relay 3:
Pin 86: Black/Green wire from blower switch
Pin 30: Black/Green wire from resistor pack
Relay 4:
Pin 86: Black/Red wire from blower switch
Pin 87A: Black/Red wire from resistor pack
Pin 30: Main power wire going to Blower Motor + Connection

Also, can anybody tell me what a healthy ohm reading is for the blower motor? Checking across the +/- terminals, I got 1.7 ohms.

One more thing: Why does the blower motor have a 30 amp fuse if it's only supposed to pull ~10-13 at most? Anything more than that and the motor is toast, right? I might just put a 15 amp fuse where the 30 amp is, and when/if it ever blows I'll know the motor is pulling too much current and it's time for a replacement.

 

[vanbcguy]

You likely won't be able to get anything useful checking for resistance across the motor. Checking current draw while running would be more valuable.

The fuse is larger as motors take considerably more current to start up than they do to run.

Virtually any time you're blowing resistor packs or melting switches the motor is on its last legs.

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[thechoochlyman]

I'm gonna have to get a more substantial multimeter to check that out, my current one only reads up to 10 amps.

But just to be clear, it isn't melting anything yet. Just gets rather warm during normal operation.